As for our Redeemer, etc. Mr. Cheyne suspects, with some reason, that this is "the marginal note of a sympathetic scribe, which has made its way by accident into the text." It is certainly quite unlike anything else in the song, which would artistically be improved by its removal.
If, however, it be retained, we must regard it as a parenthetic ejaculation of the Jewish Church on hearing the first strophe of the song—the Church contrasting itself with Babylon, which has no one to stand up for it, whereas it has as "Redeemer the Lord of hosts, the Holy One of Israel."